Titanium-molybdenum-chromium alloys



March 4, 1952 Ulfimafe Tensile SrrengTh(P.S.l.)

R. 1. JAFFEE 2,533,007

TITANIUM-MOLYBDENUM-CHROMIUM ALLOYS Filed Oct. 5, 1948 |2o,ooo Q/ G OTi-Mo binary O T|"MO+25/o Cr lllllllll O I 2 3 4 5 6 7 8 9 IO MolybdenumFIG.

O Ti-Mo binary A o Ti-Mo+2.5%0r

5 no G O I 2 3 4 5 6 7 8 9 IO Molybdenum 0) FIG. 2

INVENTOR. Robert I. doffee AGENTS Patented Mar. 4, 1952TITANIUM-MOLYBDENUM- CHR OMIUM ALLOYS Robert I. Jaffee, Columbus, Ohio,assignor, by mesne assignments, to Battelle Development Corporation,Columbus, Ohio, a. corporation of Delaware Application October5, 1948,Serial No. 52,961

1 Claim. 1

This invention relates to titanium base alloys and more particularly toternary alloys containing titanium, molybdenum, and chromium.

Some work has been done on certain binary alloys of titanium, but thesealloys proved to be brittle and unsatisfactory for commercial workingpractices. Because of the poor properties found by early investigationsin the titanium field, further development was discouraged and noternary alloys using titanium as a base have been made public up to thepresent time. The present invention, however, is concerned with theproduction of ternary alloys of titanium which have highly desirableproperties and which are believed to be completely new in the alloy art.

It is, therefore, an object of this invention to provide ternary alloysof titanium with molybdenum and chromium.

A further object of this invention is to produce high-strength, ductiletitanium base alloys which include chromium and molybdenum as the, onlyadded alloying ingredients.

, Yet another object of this invention is to provide titanium basealloys suitable for structural purposes.

Other advantages and purposes of the present invention will becomeapparent from the following disclosure thereof, when considered inconjunction with the accompanying drawings wherein:

Figure 1 is a graph illustrating the effect on the tensile strength ofadding 2.5% Cr to various Ti-Mo alloys, and

Figure 2 is a graph which shows the effect that the same addition toTi-Mo alloys has on the elongation of the alloys.

In general this invention relates to ternary alloys comprising 1 tomolybdenum, 0.5 to 2.5% chromium and the remainder essentially titanium.Certain advantageous elements such as oxygen, nitrogen, carbon, etc. maybe present.

The alloys of this invention may conveniently be prepared by powdermetallurgy methods. For example, several metals may be mixed together aspowders, compacted at about fifty tons per square inch, sintered in ahigh vacuum for about four hours at about 1100 0., enclosed in a steelenvelope to prevent reaction with the air, and rolled at about 750 C. to900 C., and finally stripped from the steel envelope. It will beunderstood that the various conditions enumerated annealed.

The present alloys may also be obtained by melting the component metalsinto an ingot in an arc furnace.

As an example of the beneficial effect of alloying molybdenum andchromium with titanium, Table 1 below shows ultimate tensile andductility data for a control titanium metal, for binaries of titaniumand molybdenum, and for ternaries formed by adding 2.5% chromium to theTi-Mo binaries.

Table 1 Metal 'ri+sfb% Mo+2.5% Cr LI Ti+7.5% Mo+2.5% Cr These data arefurther presented and the results illustrated in the graphs in Figures 1and 2 wherein it is clearly shown that the effect of the addition ofchromium is to increase the tensile values without producing anobjectionable decrease in ductility. The strength values of all theternary alloys are considerably in excess of the 89,000 p. s. i.possessed by the control titanium metal. At the same time the ductilityvalues are quite sufiicient to permit commercial working of the alloys.

In addition to their desirable strength and ductile properties, thealloys of the present invention have excellent strength/weight ratios,equalling or surpassing aluminum and several aluminum alloys in thisrespect. This is illustrated in Table 2 below wherein thestrength/weight ratios of Ti-Mo-Cr alloys are compared with those ofseveral aluminum alloys.

Table 2 Ratio of 0.2% Ratio of Ultimate. Alloy (as annealed) TensileStrength ggfi g g to Density Density 4, 800 l, 850 9, 600 5, 000 9. 7004, 000 15 11, 800 5, 400 Ti-2.5 MO2.5 C12... ll 25, 21,000 Ti-5.0 MO-2.5C12. 27, 800 24, 500 Ti-7.5 M02.5 Cl 26, 700 24, 000

Note-Data on aluminum and aluminum alloys were taken from 1948 editionof the ASM Handbook.

3 The Ti-Mo-Cr alloys are also heat treatable. Table 3 shows how thehardness of Ti-Mo alloys is increased by quenching from temperatures inthe range from 700 to 1000 C. and it is known that chromium additions upto 10% further enhance these heat treating characteristics.

1 Vickers Diamond Pyramid, 10 Kg. load.

All of the properties mentioned and demonstrated go to make the presentalloys valuable,

and it will be apparent that these alloys are suited for use asstructural materials, for example in aircraft structural parts. Otheruses 4 and applications are available and will readily suggestthemselves to persons skilled in the art.

What is claimed is: An alloy comprising 2.5 to 7.5% molybdenum,

0.5-2.5% chromium as the only alloying elements and the remainderessentially all titanium.

ROBERT I. JAFFEE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,551,333 Schroter et a1 Aug. 25,1925 1,562,041 Pacz Nov. 17, 1925 2,107,279 Balke et al Feb. 8, 1938FOREIGN PATENTS Number Country Date 718,822 Germany Mar. 24, 1942

